V NU Journal o f S cience, M athem atics - Physics 25 (2009) 99-105 Design o f phase-coded transmitter and high sensitive receiver o f radar system Do Trung Kien' *, Bach Gia Duong^ Nguyen Quy T huong\ Nguyen Manh Hung' ^Faculty o f Physics, College o f Science, VNU, 334 Nguyen Trai, Thanh Xuan, Hanoi, Vietnam ^Research center fo r Electronics and Telecommunications, College o f Technology, VNU 144 Xuan Thuy, Cau Giay, Hanoi, Vietnam ^Vietnam National University, 144XuafhThuy, Can Giay, Hanoi, Vietnam Received 10 June 2009; received in revised form 13 July 2009 Abstract This paper reports experimental results of a radar system design In the radar transmitter, a 13-bit Barker code with bit duration 3.24 and various other codes are generated by the microcontroller PIC16F877A, This code is then used to modulate IF 10.3 MHz to become BPSK signal A stable local oscillator is also designed by PLL, v c o , and PIC16F877A The operation frequency range of the oscillator is from 800 MHz to 900 MHz with an eưor only about ± 10 Hz A microwave power amplifier is fabricated with structure of two stages of 45 w and 90 w in case of input 300 mW In this amplifier microstrip technique is implemented for input/output matching network In the receiver, subsystem can receive and decode very small signal with amplitude from -30 dBm to -108 dBm and frequency range from 800 MHz to 900 MHz Keywords: Barker code, BPSK signal, Stable Local Oscillator, Microwave Power Amplifier ! Introduction Radar is identified as a device for detection, ranging and recognition o f variety o f targets Because of great diversity o f applications in military and civil, the designing o f radar system is usually based on purpose For radar systems in Vietnam, the research results were often used very complex schematics that limited the operation of systems Therefore, our working focuses on design radar system components using modem elecừonic devices and techniques In radar transmitter, Barker code generator, phase-coded modulator, and local oscillator can be easily created and conừolled when taking advantage o f microcontroller High power amplifier IS designed with an impedance matching using microsừip technique In receiver, we designed and fabricated successfully a very high sensitive UHF receiver model ECC-01 Specifications o f ECC-01 have more advantages than some UHF receivers that are used in Vietnam [1,2] The following sections will report and discuss our results o f these fabrications ’ Coưesponding author E-mail: dtkien@vnu.edu.vn 99 100 D T Kien et al / VNU Journal o f Science, M athematics - Physics 25 (2009) 99-105 Experim ental Block diagram o f transmitter and receiver o f a radar system is shown in the F ig.l The code used in the ữansmitter is the 13 bit Barker code {-H-Ỉ-++-++-+-+}, Aitenai Power N ị/ Code G enerator Phaie-Coded Modulator UpcoHvcnIoa IF Generator Locml Oscillator IvcoM RECEIVER LED Displiy IFLogarttliinic PLL Electronic Switching Ai DowBcoavcrtloa D«tcctor ! * R